Physical Science: Matter and Its Properties
What this domain tests
Matter is anything with mass and volume. Know the three common states: solids have definite shape and volume, liquids have definite volume but take the shape of their container, and gases fill their container. Particles in a solid are closely packed and vibrate; in a liquid they slide past each other; in a gas they move freely and far apart.
Properties and changes
Know how to describe matter with properties such as mass, volume, density, color, hardness, and magnetism. Distinguish physical changes, which do not create a new substance (melting, cutting, dissolving), from chemical changes, which do (burning, rusting, baking). Signs of a chemical change include a new color, gas bubbles, heat or light released, and a new smell. Know that mass is conserved in a closed system, and that mixtures can be separated by physical means such as filtering or evaporating.
Traps to watch for
Questions often call melting a chemical change, or say mass disappears when something burns. Another trap is confusing weight with mass, or assuming a larger object is always denser. Watch for answers that describe a state change as forming a new substance.
Rule of thumb
Ask "is it still the same stuff?" If yes, it is a physical change; if a new substance formed, it is chemical. For example, ice melting is physical because it is still water, while a nail rusting is chemical because rust is a new substance.